Electron microscopic observations of the kidney in the generalized Shwartzman reaction.

Sequential changes in the kidney during the generalized Shwartzman reaction were studied electron microscopically. The first anatomical change was infiltration of neutrophils into the glomerular capillaries. Endothelial damage was not noticeable until the capillaries were filled with fibrin deposits. Fibrin appeared in the mesangium at almost the same time as in the capillary lumina, traversing through the endothelial fenestrae. Endothelial damage was more common in the mesangial portion than in the peripheral portion of the capillaries. Severe mesangiolysis developed after loss of endothelial cells had been followed by massive penetration of intracapillary contents. Later, signs of repair were evident in some parts of the damaged endothelium. The development of cortical necrosis coincided with the appearance of mesangiolysis and arteriolar thrombotic lesions.